We don't have any support for embedded browsers in RCP applications, so the components can't be accessed by e.g. replace text or other actions. If you just need to enter a few strings, then I could recommend using the action "external input text". This lets you specify text to enter where the focus is. You would have to have some way of getting the focus into the browser, or to the component you require within the browser - using external key combination for e.g. Tab or Enter could help here. That should at least allow you to work with the browser as a part of the test.